A Method of Gain and Noise Figure Enhancement in S-Band

A method of gain and noise figure enhancement in S-band by adjusting thulium absorption overlap factor through photonic crystal fiber (PCF) is provided, the method includes the steps of doping clad with high index material, enlarging air holes surrounding doped core region of the clad, optimizing PCF geometrical structural parameters for lower than short cut-off wavelength and higher than high cut off wavelength, for bandpass of 800 nm to 1750 nm, wherein unwanted amplified spontaneous emissions (ASE) is suppressed using PCF structure to allow S-band signal to propagate with zero loss and high overlap factor.